Plasma generator, ozone generator, substrate processing apparatus and manufacturing method of semiconductor device

ABSTRACT

To provide a generator capable of generating plasma and ozone with high efficiency and easy to handle, with a simple structure. An electrode part  10  is formed of electrodes  11  and  12  without dielectric material interposed therebetween. An arc-extinguishing capacitor  13  as a charge storage part for storing charge is connected in series to the electrode part  10 . An AC power source  15  generating plasma by causing self-arc-extinguishing discharge between the electrodes  11  and  12  by applying AC voltage to charge and discharge the arc-extinguishing capacitor  13 , is connected to both ends of a circuit in which the electrode part  10  and the arc-extinguishing capacitor  13  are connected in series. The arc-extinguishing capacitor  13  and one electrode  12  of the electrode part  10  connected thereto are unitized, for making the electrode part multi-polarized. A unit is constituted of a floating electrode serving as both of the one electrode  12  of the electrode part  10  and one electrode of the arc-extinguishing capacitor  13 , an insulating material provided around the floating electrode and a grounding electrode provided around the insulating material.

TECHNICAL FIELD

The present invention relates to a plasma generator, and an ozonegenerator and a substrate processing apparatus, and particularly to anapparatus appropriate for generating plasma and ozone by producing anon-steady discharge in an atmospheric pressure.

BACKGROUND ART

A substrate processing apparatus functions to perform processing such asforming and improving a film on a substrate such as a semiconductorsubstrate or a glass substrate. Ozone is frequently used for theprocessing such as forming and improving the film. As a most generallyused system of generating the ozone, a system using a silent dischargeis given as an example.

In the discharge under the atmospheric pressure, usually non-steadydischarge (non-arc discharge and non-thermal plasma) is used. Thenon-steady discharge is used for the reason that there is a fear thatthrough a glow discharge and an arc discharge, a discharge breakdown(ignition) in an atmospheric pressure develops into a thermal breakdownof an apparatus, to make a steady discharge difficult to be used. Thesilent discharge is a discharge phenomenon observed under atmosphericpressure, in applying a voltage between electrodes where dielectricmaterial is inserted, and the silent discharge becomes a non-steadydischarge by the insertion of the dielectric material. Ozone isgenerated by utilizing the aforementioned discharge. In an ozonegenerator utilizing the silent discharge, specifically, as shown in FIG.21, a dielectric material 2 is provided in one (FIG. 21A) or both (FIG.21B) of a pair of parallel plate electrodes 1 and 1, and by impressingAC high voltage between the electrodes 1 and 1, a plasma discharge isintermittently caused between the electrodes 1 and 1 in the atmosphericpressure. Then, by passing oxygen O₂ or dry air in the dischargeatmosphere, ozone O₃ is generated by utilizing a high energy electron ofplasma, and a mixed gas (O₂+O₃) is obtained.

Also, in order to generate ozone, a creeping discharge which is one typeof the silent discharge is sometimes used. As shown in FIG. 22, thecreeping discharge is provided, with the dielectric material 3 putbetween a dielectric electrode 4 becoming a planar electrode at one sideand a discharge electrode 5 becoming a line electrode at the other side.Then, AC high voltage is applied between the both electrodes 4 and 5 byan AC high voltage power source 6, so as to discharge between thedischarge electrode 5 and the dielectric material 3. Then, the ozone O₃can be generated by feeding oxygen O₃ or dry air in the dischargeatmosphere 7.

The aforementioned silent discharge system has a simple structure suchthat a high voltage AC power source of 20 to 10000 Hz may be used as apower source, and it is necessary only to insert the dielectric materialbetween the electrodes at a discharge part, and embed the electrodes inthe dielectric material, and therefore the silent discharge system isexclusively utilized in the ozone generator.

As a conventional technique related to such a silent discharge, forexample, the technique recited in the patent document 1 is known. Inthis technique, granules are formed by covering entire surface of aconductor with an insulating material, and inter-electrodes of electrodepairs is packed with such granules, so that the conductor in thegranules forms a small electrode, and the insulating materialconstitutes a dielectric barrier. Dielectric barrier discharge changesthe gas into plasma in a gap between granules. Since each gap betweengranules is small, even the gas with large discharge starting voltagesuch as oxygen and nitrogen is capable of generating a uniform glowdischarge with an extremely small application power, and plasma andozone are thereby generated.

Patent document 1: Japanese Patent Laid-open No. 8-321397

DISCLOSURE OF THE INVENTION

However, in the aforementioned ozone generator utilizing the silentdischarge disclosed in the patent document 1, it is necessary that theentire surface of the conductor is covered with the insulating material,and inter-electrodes of electrode pairs is packed with the dielectricmaterial, resulting in a complicated structure. In addition, in thedielectric barrier discharge, a discharge current (plasma density) islimited by a small electrostatic capacity of the dielectric material.Therefore, although stable discharge can be induced by applying smallvoltage, a discharge energy density can not be increased. Accordingly,it is impossible to neither generate plasma with high efficiency, norgenerate ozone with high efficiency. Moreover, as described above,inter-electrodes are packed with dielectric material covered withconductor, and therefore handling is not easy.

Note that instead of the silent discharge, a short pulse discharge andan RF discharge systems can be adopted. However, in the short pulsedischarge, a high voltage short pulse generator of 10 to 1000 puls/s isrequired, thereby increasing the cost of the power source, and inaddition, a sophisticated pulse compression technology is required.Also, the RF discharge is a high frequency type of the silent discharge,in which a high frequency power supply (13.56 MHz) is required, and acapacity to limit a discharge current is shared by the dischargeelectrode (referred to as an electrode part hereafter), and therefore aplasma source having various shapes can not be formed, with constrainsof the shape of the discharge electrode. In addition, a problem commonin the short pulse discharge and the RF discharge is that an apparatusis expanded and the plasma source is difficult to be enlarged.

An object of the present invention is to provide a plasma generator anda substrate processing apparatus capable of generating plasma with highefficiency while having a simple structure, by solving theaforementioned problem of the conventional technique by separating thecapacity for liming discharge current from the discharge electrode.Also, the object of the present invention is to provide an ozonegenerator capable of generating ozone with high efficiency and asubstrate processing apparatus. Further, the object of the presentinvention is to provide a plasma generator, an ozone generator, and asubstrate processing apparatus which are easy to handle.

The present invention takes several aspects as follows.

In a first aspect, a plasma generator is provided, an electrode partconstituted of plural electrodes;

a charge storage part connected with the electrode part in series forstoring charge, and

an AC power source for applying AC voltage to a serial connectioncircuit formed of the electrode part and the charge storage part,

wherein by applying the AC voltage to the serial connection circuitformed of the electrode part and the charge storage part by the AC powersource, discharge is intermittently caused in each inter-electrodes ofthe plural electrodes of the electrode part, and plasma is therebygenerated.

When the AC voltage applied to the electrode part exceeds the dischargestarting voltage, inter-electrodes is virtually short-circuited, and theelectrode part starts discharging electric charges to generate plasma.However, since the charge storage part is connected with the electrodepart in series, the discharge is effected as long as the charge isstored in the charge storage part, and stops when the storage of chargeis completed. Thus, even when the dielectric material is not insertedbetween the electrodes, the discharge current is limited by the chargestorage part, and intermittent discharge is thereby caused.

The inter-electrodes is short-circuited, and a large current dischargeis thereby caused, and therefore the discharge energy density becomeslarger compared with that of the silent discharge. This contributes toforming plasma with high efficiency even in the atmospheric pressure.

In addition, the discharge caused between plural electrodes of theelectrode part becomes a self arc-extinguishing discharge, resulting inbeing intermittent, and extinguished before becoming an arc discharge.This contributes to reducing damage to the electrode part.

In addition, since the discharge current is limited by the chargestorage part connected to the electrode part in series, the constraintsof the electrode shape of the electrode part is eliminated, althoughthis is not the case when the charge storage part is not independentlyprovided and the discharge current is limited by the electrode part.

Note that as the plural electrodes constituting the electrode part whereheat generation occurs by discharge, a metal electrode excellent in heatreleasing property is preferable. Also, at the charge storage part,nothing is required but to store the charge and discharge the chargethus stored, and therefore the charge storage part can be constituted bya simple capacitor. In addition, the power source can be constituted byan inexpensive AC power source.

In a second aspect, an ozone generator is provided, comprising:

an electrode part constituted of plural electrodes;

a charge storage part connected with the electrode part in series, forstoring charge; and

an AC power source for applying AC voltage to a serial connectioncircuit formed of the electrode part and the charge storage part,

wherein by applying the AC voltage to the serial connection circuitformed of the electrode part and the charge storage part by the AC powersource, discharge is caused intermittently in each inter-electrodes ofthe plural electrodes of the electrode part, and ozone is generated bysupplying gas containing oxygen atom in the discharge atmosphere.

In the second aspect, ozone is generated by using plasma generated inthe first aspect, and the ozone can be generated with high efficiency.

In a third aspect, a plasma generator is provided, comprising:

an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material;

a third electrode facing the first electrode; and

a power source for applying voltage between the second electrode and thethird electrode,

wherein by such a power source, the voltage is applied between thesecond electrode and the third electrode, thereby causing dischargebetween the first electrode and the third electrode, and plasma isthereby generated. Preferably, the AC voltage is applied between thesecond electrode and the third electrode.

By providing the insulating material or the dielectric material aroundthe first electrode, and providing the second electrode therearound, thefirst electrode of the electrode part which makes pair with the thirdelectrode is unitized. This contributes to easy handling of theelectrode part and also making the apparatus compact.

In addition, by applying the voltage between the second electrode andthe third electrode, when the voltage generated between the firstelectrode and the third electrode exceeds the discharge startingvoltage, inter-electrodes of the first electrode and the third electrodeis short-circuited, to allow a large current discharge to be caused.This contributes to forming plasma with high efficiency.

In a fourth aspect, the plasma generator according to the third aspectis provided, wherein a charge storage part for storing charge is formedby the first electrode and the second electrode, with the insulatingmaterial or the dielectric material interposed between the firstelectrode and the second electrode. A unit structure can be thussimplified.

In a fifth aspect, the plasma generator according to the third aspect isprovided, wherein by applying AC voltage between the second electrodeand the third electrode, a pulse discharge is generated between thefirst electrode and the third electrode, and plasma is therebyintermittently generated. By generating the pulse discharge, damage tothe electrode part can be further reduced in generating plasma.

In a sixth aspect, the plasma generator according to the third aspect isprovided, wherein the plasma is generated in an atmospheric pressure.Even when the plasma is generated in the atmospheric pressure, dischargecaused between the first electrode and the third electrode can beprevented from developing into thermal breakdown of the apparatusthrough a glow discharge to an arc discharge, because the insulatingmaterial or the dielectric material is interposed between the firstelectrode and the second electrode constituting the electrode unit.

In a seventh aspect, the plasma generator according to the third aspectis provided, wherein the electrode unit is provided in plural numbers.By providing the electrode unit in plural numbers and making the firstelectrode and the third electrode face with each other, the electrodepart can be made multi-polarized. By making the electrode partmulti-polarized, a plasma source of any shape can be formed. Inaddition, a discharge circuit can be made by low impedance, andtherefore the plasma source with high plasma density and a large surfacearea can be realized.

In an eighth aspect, the plasma generator according to the third aspectis provided, wherein the electrode unit is provided in plural numbersaround the third electrode. Even when the electrode unit is provided inplural numbers, thereby making multi-polarized electrode, the apparatuscan be made compact by providing the plural electrode units around thethird electrode.

In a ninth aspect, the plasma generator according to the third aspect isprovided, wherein a protrusion portion or a recess portion or an openinghole is provided in a part of the third electrode faced with the firstelectrode. By providing the protrusion portion or the recess portion orthe opening hole in the part of the third electrode faced with the firstelectrode, an electric charge is concentrated there, to therebyfacilitate discharge and the plasma can be more efficiently formed.

In a tenth aspect, the plasma generator according to the third aspect isprovided, wherein the first electrode is formed in a bar-shape. Byforming the electrode in a bar-shape, the concentration of the electriccharge is realized. Therefore, the discharge between the first electrodeand the third electrode can be facilitated, and the plasma can be moreefficiently formed.

In an eleventh aspect, the plasma generator according to the thirdaspect is provided, wherein the first electrode is formed in acylinder-shape. By forming the first electrode in a cylinder shape, asource gas for generating plasma can be supplied and the gas generatedby plasma can be obtained through the cylinder of the first electrode.

In a twelfth aspect, the plasma generator according to the third aspectis provided, wherein the insulating material or the dielectric material,or/and the second electrode are formed in a cylinder shape. By formingthe insulating material or the dielectric material, or/and the secondelectrode in a cylinder shape, a multiple structure of covering theelectrode unit with a cylinder is realized, and therefore the apparatuscan be further made compact.

In a thirteenth aspect, the plasma generator according to the thirdaspect is provided, wherein at least the first electrode or/and thethird electrode are formed of metal. By forming the electrode withmetal, heat generated by discharge between the first electrode and thethird electrode can be easily released.

In a fourteenth aspect, the plasma generator according to the thirdaspect is provided, wherein the first electrode or/and the thirdelectrode are cooled by refrigerant. By cooling the electrode, the heatgenerated by discharge can be efficiently released.

In a fifteenth aspect, a substrate processing apparatus is provided,comprising:

an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material;

a third electrode facing the first electrode; and

a power source for applying voltage between the second electrode and thethird electrode,

wherein by the power source, the voltage is applied between the secondelectrode and the third electrode, discharge is caused between the firstelectrode and the third electrode, and in this discharge atmosphere, gascontaining oxygen atom is supplied, and ozone is thereby generated. Byusing the electrode unit, assembling of the apparatus is facilitated,and a compact apparatus capable of generating ozone with high efficiencycan be obtained.

In a sixteenth aspect, a substrate processing apparatus is provided,comprising:

a processing chamber for processing a substrate; and

a plasma generator for generating plasma,

wherein a substrate is processed by using a reactant obtained byexposing processing gas to the plasma generated by the plasma generator,

the plasma generator comprising:

an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material;

a third electrode facing the first electrode; and a power source forapplying voltage between the second electrode and the third electrode,wherein by applying the voltage between the second electrode and thethird electrode, discharge is caused between the first electrode and thethird electrode, and plasma is thereby generated. By using the electrodeunit, the apparatus can be easily assembled, and a compact apparatuscapable of improving the processing of the substrate can be obtained bygenerating plasma with high efficiency.

In a seventeenth aspect, a substrate processing apparatus is provided,comprising:

a processing chamber for processing a substrate; and

an ozone generator for generating ozone,

wherein by using the ozone generated by the ozone generator, thesubstrate is processed,

the ozone generator further comprising:

an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material;

a third electrode facing the first electrode; and

a power source for applying voltage between the second electrode and thethird electrode,

wherein by applying the voltage between the second electrode and thethird electrode, discharge is caused between the first electrode and thethird electrode, and in such a discharge atmosphere, gas containingoxygen atom is supplied, and ozone is thereby generated. By using theelectrode unit, the assembly of the apparatus is facilitated, and acompact apparatus capable of improving the processing of the substrateby generating ozone with high efficiency can be obtained.

In an eighteenth aspect, a method of manufacturing a semiconductordevice is provided, with a plasma generator having an electrode unitconstituted of a first electrode, an insulating material or a dielectricmaterial provided around the first electrode, and a second electrodeprovided around the insulating material or the dielectric material, anda third electrode facing the first electrode,

the method comprising the steps of:

generating plasma by causing discharge between the first electrode andthe third electrode by applying voltage between the second electrode andthe third electrode; and

processing a substrate by using a reactant obtained by exposing aprocessing gas to the plasma thus generated. By using the electrode unitand generating plasma with high efficiency, the processing of thesubstrate can be improved, and the semiconductor device with highquality can be manufactured.

In an nineteenth aspect, the method of manufacturing the semiconductordevice according to the eighteenth aspect is provided, wherein a pulsedischarge is caused between the first electrode and the third electrodeby applying AC voltage between the second electrode and the thirdelectrode, and plasma is thereby intermittently generated in the plasmagenerating step. By generating plasma by pulse discharge, damage to theelectrode part can be further reduced in generating plasma.

In a twentieth aspect, the method of manufacturing the semiconductordevice according to the eighteenth aspect is provided, wherein thesubstrate is processed in the substrate processing step by using ozoneobtained by exposing gas containing oxygen atom to atmosphere where thedischarge is caused. By generating ozone with high efficiency, theprocessing of the substrate is improved, and the semiconductor devicewith high quality can be manufactured.

In a twenty-first aspect, the method of manufacturing the semiconductordevice according to the eighteenth aspect is provided, wherein theprocessing refers to a surface improving processing of a substrate or athin film formed on the substrate. By generating plasma with highefficiency, an excellent surface improvement can be realized.

In a twenty-second aspect, the method of manufacturing the semiconductordevice according to the eighteenth aspect is provided, wherein theprocessing refers to a film forming processing to form a CVD film on thesubstrate. By generating plasma with high efficiency, an excellent CVDfilm can be formed.

In a twenty-third aspect, the method of manufacturing the semiconductordevice according to the eighteenth aspect is provided, wherein theprocessing refers to an etching processing to etch the film formed onthe substrate. By generating plasma with high efficiency, an excellentfilm etching can be realized.

In a twenty-fourth aspect, the method of manufacturing the semiconductordevice according to the eighteenth aspect is provided, wherein theprocessing refers to a substrate washing processing. By generatingplasma with high efficiency, an excellent substrate washing can berealized.

In a twenty-fifth aspect, a method of manufacturing a semiconductordevice is provided,

the semiconductor device comprising:

an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material; and a third electrode facing the first electrode,

the method of manufacturing the semiconductor device comprising thesteps of:

processing a substrate by supplying gas to the substrate;

generating plasma between the first electrode and the third electrode byapplying voltage between the second electrode and the third electrode;and

decomposing an exhaust gas generated when processing the substrate byusing the plasma. By generating plasma with high efficiency, anexcellent exhaust gas decomposition is realized.

In a twenty-sixth aspect, a plasma discharger is provided, comprising:

an electrode part constituted of plural electrodes;

a charge storage part connected with the electrode part in series, forstoring charge; and

a terminal connected to an AC power source provided in the electrodepart and the charge storage part,

wherein by applying AC voltage between the electrode part and the chargestorage part through the terminal, discharge is intermittently causedbetween the plural electrodes of the electrode part, and plasma isthereby generated. By providing the insulating material or thedielectric material around the first electrode, and providing the secondelectrode therearound, the first electrode which makes pair with thethird electrode is unitized, and handling of the electrode part isthereby facilitated. In addition, by applying the AC voltage between thesecond electrode and the third electrode, when the AC voltage generatedbetween the first electrode and the third electrode exceeds thedischarge starting voltage, inter-electrodes of the first electrode andthe third electrode is short-circuited, thereby allowing a large currentto occur, and the plasma can be formed with high efficiency.

In a twenty-seventh aspect, an electrode unit for generating plasma isprovided, comprising a first electrode, an insulating material or adielectric material provided around the first electrode, and a secondelectrode provided around the insulating material or the dielectricmaterial. By applying voltage between the third electrode and the secondelectrode, with the first electrode constituting the electrode unitfaced with the third electrode, discharge is caused between the firstelectrode and the third electrode, and plasma can thereby be generated.Since parts other than the third electrode for generating plasma isunitized, handling is easy.

In a twenty-eighth aspect, a plasma generator is provided, comprising:

an electrode part constituted of plural electrodes;

plural charge storage parts connected with the electrode part in series,for storing charge; and

an AC power source for applying AC voltage to a circuit, to which pluralserial connection parts formed between the electrode part and the pluralcharge storage parts are connected in parallel,

wherein by applying the AC voltage to the circuit, to which the pluralserial connection parts formed between the electrode part and the pluralcharge storage parts are connected in parallel, discharge isintermittently caused in each inter electrodes of the plural electrodesof the electrode part, and plasma is thereby generated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an equivalent circuit diagram of a plasma generator accordingto an embodiment.

FIG. 2 is a view showing a relation between an applied voltage and aplasma injection power according to the embodiment.

FIG. 3 is a block diagram of a capacitive coupling electrode accordingto the embodiment, and FIG. 3A is a vertical sectional view, and FIG. 3Bis a perspective view.

FIG. 4 is a view showing a multi-polarized structure according to theembodiment in which plural capacitive coupling electrodes are arranged.

FIG. 5 is an entire block diagram of a multi-polarized plasma generatorin which the plural capacitive coupling electrodes according to theembodiment are arranged.

FIG. 6 is a plan view of an example of a multi-polarized arrangementaccording to the embodiment.

FIG. 7 is a plan view of the example of the multi-polarized arrangementaccording to the embodiment.

FIG. 8 is a sectional view of the multi-polarized arrangement accordingto the embodiment.

FIG. 9 is an explanatory view of an electrode part constituted of acounter electrode and a floating electrode, wherein FIG. 9A is abackside view of the counter electrode, and FIG. 9B is a side view ofthe electrode part.

FIG. 10 is an explanatory view showing a gas lead-in method according tothe embodiment.

FIG. 11 is an explanatory view showing the gas lead-in method accordingto the embodiment.

FIG. 12 is an explanatory view showing the gas lead-in method accordingto the embodiment.

FIG. 13 is an explanatory view showing the gas lead-in method accordingto the embodiment.

FIG. 14 is a block diagram of a reaction furnace of a verticaldispersion apparatus according to the embodiment.

FIG. 15 is a block diagram of the reaction furnace of a CVD apparatusaccording to the embodiment.

FIG. 16 is a block diagram of the reaction furnace of a sheet wafer-feedtype CVD apparatus according to the embodiment.

FIG. 17 is a block diagram of a washing apparatus according to theembodiment.

FIG. 18 is a block diagram of a sheet-wafer-feed type etching apparatusaccording to the embodiment.

FIG. 19 is an etching (ashing) principle diagram by using ozoneaccording to the embodiment.

FIG. 20 is a block diagram of an example of the sheet wafer-feed typeCVD apparatus provided with an exhaust gas processing apparatusaccording to the embodiment.

FIG. 21 is a principle diagram of a silent discharge system of aconventional example.

FIG. 22 is a principle diagram of a creeping discharge of theconventional example.

FIG. 23 is a view showing an example of a structure ofmulti-polarization in which plural capacitive coupling electrodes arearrayed according to a modified example of the embodiment.

FIG. 24 is an equivalent circuit diagram of the multi-polarized plasmagenerator of FIG. 4

DESCRIPTION OF REFERENCE NUMERALS

-   10 electrode part-   11, 12 electrode-   13 arc-extinguishing capacitor (charge storage part)-   15 AC power source-   20 electrode unit-   22 insulating material-   23 second electrode-   34 counter electrode (third electrode)

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be explained hereinafter.

FIG. 1 is an equivalent circuit diagram explaining a principle of aplasma generator.

A plasma generator comprises an electrode part 10 constituted of twocounter electrodes 11 and 12; an arc-extinguishing capacitor 13(capacity C) as an charge storage part connected with the electrode part10 in series, for storing charge; terminals 14 and 14 connected to bothends of a serial circuit of the electrode part 10 and thearc-extinguishing capacitor 13; an AC power source 15 for applying ACvoltage between the electrode part 10 and the arc-extinguishingcapacitor 13 through the terminals 14 and 14; and a power-assistingcapacitor 16 (capacity C_(O)) connected to the AC power source 15 inparallel, for assisting power by stabilizing power supply voltage. Twoelectrodes 11 and 12 are formed of metal electrode, for example. Asmetal, copper, stainless steel and so forth can be used. No dielectricmaterial exists between the metal electrodes 11 and 12. Atmospheric airexists between the metal electrodes 11 and 12, to thereby form acapacitor (capacity Cg), and discharge is caused between the metalelectrodes 11 and 12. The AC power source 15 is constituted of a highvoltage AC power source, and the AC voltage is set to be about severalKv or more, and an AC frequency is set to be 50 to 10000 Hz, forexample, although different depending on the size of a discharge gap G.By applying the AC voltage between the electrode part 10 and thearc-extinguishing capacitor 13 by the AC power source 15, the dischargeis intermittently caused between the electrodes 11 and 12 of theelectrode part 10, and the plasma is thereby generated.

A principle of causing an intermittent discharge will be explained byusing FIG. 2 showing an applied voltage and a plasma injection power(corresponding to discharge current). An axis of ordinate of FIG. 2Ashows the applied voltage by the high voltage AC power source 15supplied between the electrodes 11 and 12, and meanwhile the axis ofordinate of FIG. 2B shows a plasma injection power P injected betweenthe electrodes 11 and 12, respectively. An axis of abscissa shows a timein each of FIG. 2A and FIG. 2B. When an applied voltage V_(s) is smallerthan a discharge starting voltage ±V_(d) between the electrodes 11 and12, the plasma injection power P maintains a zero level. When theapplied voltage V_(s) exceeds the discharge starting voltage ±V_(d),inter-electrodes 11 and 12 is virtually short-circuited, simultaneouslywith the start of discharge, to allow a large current to flow. Triggeredby this current, storing of charge in the arc-extinguishing capacitor 13is started. When the arc-extinguishing capacitor 13 is fully charged,the current stops flowing and the discharge thereby stops. Specifically,the discharge becomes intermittent, while the discharge is effected aslong as the charge is stored in arc-extinguishing capacitor 13.

In a discharge circuit comprising the electrode part 10 constituted ofthe electrodes 11 and 12, and the arc capacitor 13 connected thereto inseries., after discharge breakdown (ignition) between the electrodes 11and 12, the voltage of the arc capacitor 13 is increased, and a selfarc-extinguishing discharge can be executed so as to speedily extinguishan arc, simultaneously with the completion of charge. Thus, when the ACvoltage is applied, short pulse discharge is repeated every half cycle.When a discharge circuit resistance is at a zero level, power injectedbetween the electrodes 11 and 12 becomes equal to a charging energy ofthe arc-extinguishing capacitor 13. Accordingly, when a charge storagefunction to store the charge in the arc-extinguishing capacitor 13 isincreased, the power injected between the electrodes 11 and 12 can bemade larger, and a discharging energy density can be increased.

As described above, an electrode of the discharge circuit in theatmospheric pressure is constituted of the serial connection circuit ofthe electrode part 10 and the arc-extinguishing capacitor 13. Therefore,only by applying the AC voltage, the discharge becomes the selfarc-extinguishing discharge of extinguishing arc before switching from aglow discharge to an arc discharge, with little damage to the electrodepart 10. In addition, no dielectric material exists between theelectrodes 11 and 12, and inter-electrodes 11 and 12 is short-circuitedat starting discharge, thereby realizing a quick large currentdischarge. Therefore, the discharging energy density is larger than thesilent discharge, and plasma can be formed in the atmospheric pressurewith high efficiency.

In addition, the discharge current is limited by electrostatic capacityof the arc-extinguishing capacitor 13 connected to the electrode part10, the electrode part 10 serving as a plasma source is released fromthe constrains. Therefore, the plasma source becomes free from theconstrains of the shape of the electrodes 11 and 12, which is requiredfor determining the electrostatic capacity for limiting the dischargecurrent. Accordingly, compared with the RF discharge system in which theelectrostatic capacity liming the discharge current is determined by theshape of the electrode, flexibility in designing of the plasma sourcecan be increased.

Moreover, in the apparatus incorporating the discharge circuit tointermittently cause discharge between the electrodes 11 and 12 of theelectrode part 10, the ozone generator for generating ozone O₃ bysupplying the gas containing oxygen atom O₂ in the discharge atmospherecan be constituted.

In this way, in the aforementioned self arc-extinguishing dischargesystem, the electrode part 10 and the arc-extinguishing capacitor 13 areconnected in series. However, specifically, the electrode of theelectrode part 10 and the arc-extinguishing capacitor 13 may beseparated from each other, although it is also possible to integrallyform the electrode of the electrode part 10 and the arc-extinguishingcapacitor 13.

FIG. 3 shows a block diagram of the electrode unit in which an electrode12 which is one of the electrodes constituting the electrode part 10 andthe arc-extinguishing capacitor 13 are integrally formed. Here, theelectrode unit is called a capacitive coupling electrode. A capacitivecoupling electrode 20 means that capacity C constituted of a floatingelectrode 21, an insulating material 22, and a grounding electrode 23 iscoupled to the floating electrode 21. FIG. 3A is a vertical sectionalview of the capacitive coupling electrode 20, and FIG. 3B is aperspective view of the capacitive coupling electrode 20. The capacitivecoupling electrode 20 is constituted of the floating electrode 21 as afirst electrode, the insulating material 22 provided around the floatingelectrode 21, and the grounding electrode 23 as a second electrodeprovided around the insulating material 22. Specifically, the floatingelectrode 21 formed of metal having a bar shape is arranged in thecenter as a core so as to be an electrically isolated state from theentire discharge circuit, the insulating material 22 is wound around thecore in a cylinder shape so as to surround this core, and further thegrounding electrode 23 made of metal having a cylinder shape is woundaround the outside of the insulating material 22. The insulatingmaterial 22 may be a dielectric material, or may be constituted by paperor cloth, and so forth, containing an electrolyte. The floatingelectrode 21 becomes one of the electrodes constituting the electrodepart 10, and a capacitor having capacity C constituted of the floatingelectrode 21, the insulating material 22, and the grounding electrode 23becomes the aforementioned arc-extinguishing capacitor 13. In this way,one of the electrodes constituting the electrode part and thearc-extinguishing capacitor are integrally constituted. This contributesto preparing a compact capacitive coupling electrode 20.

A specific example of the capacitive coupling electrode is shown asfollows. A silicone thermal contraction tube as the dielectric materialis wound around a copper rod of Φ2 mm having a predetermined length, anda copper foil is wound thereon. Capacity of the arc-extinguishingcapacitor is 20 Pf at 100 kHz. Note that Teflon thermal contraction tubemay be used as the dielectric material other than the silicone thermalcontraction tube.

By using the capacitive coupling electrode 20, the substrate processingapparatus equipped with the plasma generator, the ozone generator, and aplasma/ozone generator can be constituted. Further, by using the plasmagenerator, the method of manufacturing the semiconductor device toperform substrate processing can be executed.

The aforementioned capacitive coupling electrode 20 can be mademulti-polarized by aligning in plural numbers. Generally, the capacitivecoupling electrode 20 is not singly used, but the plasma generator isconstituted by aligning plural capacitive coupling electrodes 20 inparallel.

FIG. 4 shows an example of a basic structure of such a multi-polarizedplasma generator, in which each floating electrode 21 and counterelectrodes 34 common thereto are brought into contact with a refrigerant36 to release heat which is generated in the discharge electrode bydischarge. When ozone O₃ is generated from oxygen O₂ by using the plasmagenerator, the ozone thus generated is not required to be thermallydecomposed, and therefore it is particularly effective to cool theelectrodes 34 and 21. Note that FIG. 4 shows the basic structure, andtherefore an outer shape of the entire body of the apparatus is omitted.Detailed explanation will be followed hereunder.

The plasma generator comprises an insulating block 31 in a centerportion, an upper refrigerant jacket 32 in an upper portion, and a lowerrefrigerant jacket 33 in a lower portion, respectively. The pluralcapacitive coupling electrodes 20 are fixed to the insulating block 31in an upright state. The insulating block 31 is covered by a metalcommon grounding electrode 35, and by the common grounding electrode 35grounding electrodes 23 of the plural capacitive coupling electrodes 20are connected in parallel. In addition, the insulating block 31 isformed of the insulating material such as PFC (perf luorocarbon), andthe lower refrigerant jacket 33 filled with a refrigerant 36 is providedin the lower portion. The plural capacitive coupling electrodes 20 areburied in the insulating block 31, so that one end 21 a of each floatingelectrode 21 constituting the capacitive coupling electrode 20 protrudesin a discharge space 37 formed between the capacitive coupling electrode20 and a common counter electrode 34 from an upper surface of theinsulating block 31, and the other end 21 b is in contact with therefrigerant 36 of the lower refrigerant jacket 33. The floatingelectrode 21 is cooled by the refrigerant 36 in the lower refrigerantjacket 33. Height of one end 21 a of each floating electrode 21protruded from the upper surface of the insulating block 31 is adjustedso as to have the same surface level. The discharge space 37 in whichplural floating electrode 21 protrude with the same surface level isformed in a straight state. The upper refrigerant jacket 32 is filledwith the refrigerant 36 inside. The refrigerant jacket 32 is arranged insuch a manner as to face one end 21 a of the protruded floatingelectrode 21. The entire surface of the upper refrigerant jacket 32 isformed of a metal counter electrode 34, and the counter electrode 34 iscooled by the refrigerant in the upper refrigerant jacket 32.

A high voltage AC power source 15 is connected between the counterelectrode 34 and the grounding electrode 23, and the power assistingcapacitor 16 is connected to the high voltage AC power source 15 inparallel. In order to stably apply the high voltage AC power supply,capacity C₀ of the power supply assisting capacitor 16 may be setsatisfying the formula as follows:C₀=Σc_(i)   (Formula 1)where C_(i) is the arc-extinguishing capacity of the capacitive couplingelectrode 20, and ΣC_(i) is a total sum of the arc-extinguishingcapacity of the capacitive coupling electrode 20 connected in parallel.

By applying high voltage AC power supply, discharge is caused in eachdischarge gap G between the counter electrode 34 and the floatingelectrode 21, and the plasma is thereby generated. At this time, heat isgenerated in the counter electrode 34 and the floating electrode 21,however the electrodes 34 and 21 thus generating heat are cooled bybeing brought into contact with the refrigerant 36. When the counterelectrode 34 and the floating electrode 21 are formed of metal, the heatcan be easily removed by cooling.

FIG. 24 is an equivalent circuit diagram of the multi-polarized plasmagenerator of FIG. 4. The plasma generator comprises an electrode part 10constituted of one counter common electrode 11 and plural individualelectrodes 12 (12 a to 12 e); arc-extinguishing capacitors 13 (13 a to13 e) (capacity C) as plural charge storage parts connected in serieswith the plural individual electrodes 12 constituting the electrode part10, for storing charge; terminals 14 and 14 connected to both ends of acircuit in which a serial connection part of the electrode part 10 andthe arc-extinguishing capacitor 13 are connected in parallel; an ACpower source 15 for applying AC voltage between the electrode part 10and the arc-extinguishing capacitor 13 via the terminals 14 and 14; anda power supply assisting capacitor 16 (capacity C₀) connected to the ACpower source 15 in parallel, for assisting power supply by stabilizingthe power supply voltage. The one common electrode 11 and the pluralelectrodes 12 are formed of metal electrode, for example. As such metal,copper and stainless steel and so forth can be used. No dielectricmaterial exists between the metal electrodes 11 and 12. The atmosphericair exists between the metal electrodes 11 and 12, to thereby form acapacitor (capacity Cg), and the discharge is thereby caused between themetal electrodes 11 and 12. The AC power source 15 is formed of highvoltage AC power source, and although different according to the size ofthe discharge gap G, the AC voltage is, for example, about several kV ormore and an AC frequency is from 50 to 10000 Hz. By applying the ACvoltage between the electrode part 10 and the arc-extinguishingcapacitor 13 by the AC power source 15, discharge is intermittentlycaused between the plural electrodes 11 and 12 of the electrode part 10,and plasma is thereby generated.

FIG. 5 specifically shows a block diagram of the aforementionedmulti-polarized plasma generator applied to the ozone generator.

The ozone generator comprises a container 30 containing theaforementioned upper and lower refrigerant jackets 32 and 33 and theinsulating block 31. The counter electrode 34 is not provided on theentire surface of the upper refrigerant jacket 32, but commonly providedonly on the counter surface to the floating electrode 21, and connectedto a terminal 38 which is one of the terminals for high voltage AC powersupply provided outside the container 30 in such a manner as to be takenout from the container 30. Also, the common grounding electrode 35 isnot provided around the insulating block 31, but provided inside of theinsulating block 31, in the profile of connecting the groundingelectrode 23 of each capacitive coupling electrode 20 in parallel, andis taken out from the container 30 and connected to the terminal 39which is the other terminal for high voltage AC power supply providedoutside the container 30. In the container 30, a supply port 41 forsupplying O₂ communicating with the discharge space 37 in a straightform and an exhaust port 42 for exhausting ozone are provided. Inaddition, a refrigerant supply port 43 is provided in the upperrefrigerant jacket 32, and a refrigerant exhaust port 44 is provided inthe lower refrigerant-jacket 33. Then, by connecting the upperrefrigerant jacket 32 and the lower refrigerant jacket 33 by acoil-shaped refrigerant pipe 45 outside the container 30, therefrigerant 36 such as pure water is circulated.

The high voltage AC power source is connected between the terminal 38connected to the common counter electrode 34, and the terminal 39connected to the grounding electrode 23 of the capacitive couplingelectrode 20 through the common grounding electrode 35, discharge iscaused between each floating electrode 21 and the counter electrode 34.When the voltage is applied between the terminals 38 and 39, asexplained in FIG. 2, the discharge is caused at the discharge startingvoltage between the electrodes 34 and 21. However, such a discharge isterminated simultaneously with completion of the charge into thearc-extinguishing capacitor mounted to the capacitive coupling electrode20. As shown in FIG. 5, when the plasma generator is multi-polarized,the discharge is caused between the electrodes 34 and 21 of each of thecapacitive coupling electrodes 20, before and behind each other, and thearc is extinguished after constant elapsed time. This is because thereis a variation in discharge gap G. When oxygen O₂ or dry air is suppliedto the discharge space 37 from the supply port 41, the oxygen O₂ isefficiently converted into ozone mixed gas (O₂+O₃) in the dischargespace 37, and exhausted from the exhaust port 42 of the container 30.According to this embodiment, by making the plasma generatormulti-polarized by using plural capacitive coupling electrodes 20, theplasma source having large area can be realized. In addition, thecapacitive coupling electrodes 20 are connected in parallel, and thiscontributes to forming the discharge circuit by low impedance, therebyrealizing the plasma source having high density and large area.Accordingly, ozone can be generated with high efficiency.

Also, according to this embodiment, plural electrode parts are arrangedpoint to point so as to be longitudinally arrayed or developed in aplane, constituted of the floating electrodes 21 arranged by protruding,and a counter part of the counter electrode 34 opposed to the floatingelectrodes 21. In the silent discharge and the RF discharge, when evenone place exists between parallel flat electrodes, which becomes narrowdue to distortion or bent and on which the charge is likely to beconcentrated, the discharge is deviated due to concentration of thecharge, and it is unavoidable that the plasma is un-uniformly produced.Meanwhile, contrary to the above case, in the embodiment, totallyuniform plasma is formed by making the charge concentrated on the dottedelectrode parts formed with the counter part of the counter electrode,to deviate the discharge per each unit of capacitive coupling electrode,thereby generating plasma with high efficiency. In addition, a totallyun-uniform plasma is formed by making the electrode partsmulti-polarized so as to be longitudinally arrayed or developed in aplane. Accordingly, the parallel flat electrode is not required like thesilent discharge and the RF discharge, and even if the distortion orbent is generated in the common counter electrode 34, a large currentdischarge is ensured at each electrode part, and therefore the plasmasource having high density and large area can be realized.

Note that as the refrigerant 36, a material of high insulation such aspure water needs to be used so as not to short-circuit between theelectrodes 34 and 21, or by interposing the insulating material betweenthe refrigerant 36 and the electrode 34, and between the refrigerant 36and the floating electrode 21, the refrigerant 36 is prevented fromdirectly touching on the electrodes 34 and 21. In the figure, by formingthe refrigerant pipe 45 connecting the electrodes 34 and 21 touching onthe refrigerant jackets 32 and 33, into a coil shape, the refrigeranthas a reactance component, thereby having an insulation property interms of high frequency. Moreover, as a source gas for generating ozone,oxygen O₂ is predominantly used. However, the oxygen is not required tobe 100%. Inert gas such as Ar and N₂ may be contained in dry air oroxygen O₂ for stabilizing plasma.

Incidentally, as one of the arrangement of the plural capacitivecoupling electrodes 20, the plural capacitive coupling electrodes 20 areerected along a gas flow direction, as shown in FIG. 4 and FIG. 5, andarrayed in a straight line by arranging the height of each head.However, the arrangement is not limited thereto but several modifiedexamples are considered as follows. For example, the capacitive couplingelectrodes may be arrayed with further planar spread, or may be arrayedso as to lie on the same plane. Various specific examples of such anarrangement are shown From FIG. 6 to FIG. 8.

FIG. 6 is a plan view of the arrangement of the capacitive couplingelectrode having planar spread. The erected capacitive couplingelectrodes 20 are arranged on a grid. According to such an arrangement,discharge area can be expanded in a plane form, and the plasma sourcehaving high density and large area can thereby be realized.

FIG. 7 is also a plan view of the arrangement of the capacitive couplingelectrode having planar spread. However, the plural rows of erectedplural capacitive coupling electrodes 20 are lined up in a lateral row,and the position of the capacitive coupling electrode 20 of the adjacentrow corresponding to the gap is deviated, so as to fill the gap betweenthe capacitive coupling electrodes of each row. Thus, even when the gasslips through one of the capacitive coupling electrode parts 20, doesnot fail to pass through the other capacitive coupling electrode 20.This contributes to the plasma source having higher density and largerarea.

FIG. 8 is a plan view of the arrangement of the capacitive couplingelectrodes arrayed on the same plane. Note that in this case, thearrangement of the capacitive coupling electrodes 20 is not limited to aplanar array but can be enlarged in a 3-dimensional array by laminatingthe capacitive coupling electrodes 20.

In this arrangement, a cylindrical container 50 is provided formaintaining the axial direction of the capacitive coupling electrode 20in a diameter direction. A circular inside refrigerant jacket 52 isarranged in a center portion of the cylindrical container 50, an annularinsulating block 51 is concentrically arranged outside the insiderefrigerant jacket 52, and an outside refrigerant jacket 53 isconcentrically arranged outside the insulating block 51. In the annularinsulating block 51, plural capacitive coupling electrodes 20 areradially arranged, with the circular inside refrigerant jacket 52 as acenter. In addition, a cylindrical common counter electrode 54 isprovided on an outer periphery of the inside refrigerant jacket 52, soas to be connected to one terminal 38 for the high voltage AC powersource. A common grounding electrode 55 is provided in an inner part ofthe annular insulating block 51 so as to connect the groundingelectrodes 23 constituting each capacitive coupling electrode 20 inparallel. Then, the common grounding electrode 55 is connected to theother terminal 39 for the high voltage AC power source. The commoncounter electrode 54 is cooled by the inside refrigerant jacket 52, andthe floating electrode 21 of the capacitive coupling electrode 20 iscooled by the outside refrigerant jacket 53, respectively.

Note that connection lines to the terminals 38 and 39 for high voltageAC power source from each electrode 54 and 55 are shown in the figurefor convenience. However, actually such connection lines are arranged soas to be connected to gas lead-in side or gas lead-out side provided onan end portion of the container not shown. A discharge space 57 formedbetween the common counter electrode 54 and the insulating block 51,into which one end 21 a of the floating electrode 21 protrudes andthrough which gas passes, is formed in an annular shape or a deepcylindrical shape. When the generator with this arrangement is used asthe ozone generator, the supplied oxygen O₂ passes through the dischargespace 57 in a vertical direction with respect to the sheet surface ofFIG. 8. This embodiment is different from the structure of FIG. 5 onlyin the arrangement of the capacitive coupling electrode 20, andoperation and other features are the same as those of FIG. 5.

According to an example of the arrangement of the capacitive couplingelectrode of this embodiment, by radially arranging the pluralcapacitive coupling electrodes, the plasma generator or the ozonegenerator can be formed in a cylindrical shape in the same way as thegas supply pipe. This is considered to be an essential factor to makethe apparatus compact.

Note that as the arrangement of the capacitive coupling electrodes 20,it can be arrayed in a helical state or in a laminar state, other thanthe aforementioned radial state. In addition, the common counterelectrode 54 may not be formed into a cylindrical shape but may beformed into a solid bar shape, when it is not required to be cooled frominside. In this case, preferably, the bar-shaped common counterelectrode 54 is cooled from outside by making the end portion of thebar-shaped common counter electrode 54 touch on the refrigerant. Also,in the case of this embodiment, the capacitive coupling electrodes 20shown in the figure can be arranged in a three dimensional array asshown in FIG. 6 or FIG. 7. In addition, in stead of forming thecapacitive coupling electrodes 20 shown in the figure into a bar shape,but it can be formed into a plane shape extending in a directionperpendicular to the face of the sheet, and the container 50 can beformed into a cylindrical shape. Further, with the capacitive couplingelectrode 20 in a state of bar shape, it may not arranged in a threedimensional array but arranged in a single array on the same surface, tothereby form the container 50 into a flat structure without depth.

In the aforementioned embodiment, not only the counter part but also thewhole surface of the counter electrode is formed by a flat surface ineach of the common counter electrodes 34 and 54 arranged so as to facethe floating electrode 21, although not limited to the flat surface. Forexample, the counter part may be formed in protrusion or recess, oropening hole may be provided.

FIG. 9 shows an example of the counter electrode 64 having suchprotrusion/recess parts. FIG. 9A is a backside view of the counterelectrode 64 viewed from the side of the floating electrode 21, and FIG.9B is a sectional view of the counter electrode 64 and a side view ofthe floating electrode 21 viewed from the side. In the counter partnearest to the floating electrode 21, the counter electrode 64 may haveprovided thereon an opening hole 65 passing through the common counterelectrode 64, a semi-spherical protrusion 66, a bar-shaped protrusion67, a ring-shaped protrusion 68 recessed in the center. The dischargefrom the flat surface without protrusion/recess is hard to be caused.However, by intentionally preparing the aforementioned opening holes 65and the protrusions 66 to 68, so as to induce discharge from theseparts, the charge can be concentrated on the opening hole 65 and theprotrusions 66 to 68, and the discharge from side of the counterelectrode 64 can be facilitated. Accordingly, the plasma can be furtherefficiently generated.

In the aforementioned embodiment, explanation is given to a case of agas lead-in direction to the discharge space 37, in which the gas flowslinearly in one direction. However, when the floating electrode 21 ofthe capacitive coupling electrode 20 is formed in a cylindrical shape,and a gas flow path is formed in the floating electrode 21 thus formed,or when the opening hole 65 for charge concentration is provided on thecounter electrode 64 as described above, the gas lead-in direction canbe changed so as to flow on nonlinear line. FIG. 10 and FIG. 13 show themodification example of such a gas lead-in direction. Note that in thesefigures, the capacitive coupling electrode 20 is shown by picking up oneof the multi-polarized arrays thereof, for convenience.

In FIG. 10, the floating electrode 24 is formed in a cylindrical shape,having the flow path 25 inside, and the gas generated as a reactant suchas ozone O₃ is obtained through the floating electrode 24. Basicstructure of FIG. 10 is the same as that of FIG. 5, and a differentpoint is that the floating electrode 24 is formed in a cylindrical shapeas described above. In addition, a lower end 24 b of the floatingelectrode 24 of the opposite side constituting the capacitive couplingelectrode 20 is extended so as to pass through the lower refrigerantjacket 33, and a lower space 71 for flowing the gas thus generated isformed in an end point of the extension, separately from the dischargespace 37 formed in an upper end of the floating electrode 24. A lowerwall 30 b of the container is surrounded by a second insulating block72, the lower refrigerant jacket 33 being formed by the insulating block31 and the second insulating block 72.

By leading-in oxygen O₂ as a source gas into the discharge space 37above the floating electrode 24 including the discharge gap G, ozone O₃as a generated gas is generated by the discharge gap G. Then, the ozoneO₃ thus generated is made to flow to the lower space 71 under thefloating electrode 24 through the cylindrical floating electrode 24, andtaken out from the apparatus. In this case, when the electrode part ismade multi-polarized, a part of oxygen as a source gas is led-outtogether with ozone O₃, thereby reducing the number of times the oxygenO₂ touches on plasma. However, the generated ozone O₃ is quicklyled-out, and therefore possibility that the generated ozone O₃ isdecomposed by a foreign matter and heat is reduced instead.

The structure of FIG. 11 is the same as that of FIG. 10, however, thedifferent point is that in FIG. 11, the oxygen O₂ as a source gas issupplied through the cylindrical floating electrode 24. The source gasis made to flow to the lower space 71 under the floating electrode 24,and led-in the discharge space 37 through the floating electrode 24. Thegas O₃ thus generated flows in the discharge space 37 above the floatingelectrode 24 including the discharge gap G. In this case, most of theoxygen O₂ as a source gas is led-in between the electrodes 34 and 24,and therefore the number of times the oxygen O₂ touches on plasma isincreased. However, the possibility that the ozone O₃ thus generated isdecomposed by a foreign matter and heat is also increased, instead.

In FIG. 12, the opening hole 65 is provided on the counter part of thecounter electrode 34, and the source is supplied to the discharge space37 through the counter electrode 34.

The basic structure of FIG. 12 is the same as that of FIG. 5, and thedifferent point is that in FIG. 12, as described above, the opening hole65 is provided for concentrating the charge on the counter electrode 34,and the opening hole 65 serves also as the flow path to lead-in thesource gas into the discharge space 37. The refrigerant jacket 32 withcounter electrode 34 on the lower surface is provided between an upperwall 30 a of the container 30 and the insulating block 31 provided withthe capacitive coupling electrode 20, for leading-in the source gas intothe discharge space 37 from the opening hole 65. Then, an upper space 73is formed between the refrigerant jacket 32 and the upper wall 30 a, andthe discharge space 37 is formed between the refrigerant jacket 32 andthe insulating block 31.

When the source gas is supplied from the side of the counter electrode34, oxygen O₂ as a source gas is led-in the upper space 73, and suppliedto the discharge space 37 through the opening hole 65 provided on thecounter electrode 34. In the same way as shown in FIG. 11, instead ofincreasing the number of times the source gas touches on plasma, theozone O₃ thus generated is easily decomposed by a foreign matter andheat.

The structure of FIG. 13 is the same as that of FIG. 12, however thedifferent point is that in FIG. 13, the opening hole 65 is provided onthe counter part of the counter electrode 34, so that the gas thusgenerated is exhausted toward the counter electrode 34. When the gasthus generated is exhausted toward the counter electrode 34, a mixed gas(O₂+O) containing ozone O₃ as a generated gas is exhausted from theupper space 73 through the opening hole 65. In the same way as shown inFIG. 10, instead of reducing the number of times the source gas toucheson plasma, decomposition of the ozone O₃ thus generated due to heat anda foreign matter is hard to occur.

Any one of the aforementioned plasma generators is made compact, eachstructure (design) having an enhanced degree of freedom, and thereforecan be easily installed on a dispersion apparatus, a vertical CVDapparatus, a sheet wafer-feed type CVD apparatus, a washing apparatus,an etching (ashing) apparatus and an exhaust gas processing apparatus.Next, an example, to which the aforementioned plasma generator isapplied, will be explained.

FIG. 14 shows an example of the structure of a reaction furnace 80 of avertical dispersion apparatus which functions to oxidize with ozone. Thereaction furnace 80 comprises a reacting tube 81 in which a boat 90having a plurality of substrates W stacked therein is inserted, with aninsertion port sealed by a seal cap 91; a heater 82 provided on an outerperiphery of the reacting tube 81, for heating the substrate W; a gassupply pipe 83 for supplying gas to the reacting tube 81; and an exhaustpipe 84 for exhausting an atmosphere within the reacting tube 81. Anozone generator 100 of the embodiment is provided in the gas supply pipe83 communicating to the reacting tube 81.

When ozone O₂ is supplied to the ozone generator 100 from the gas supplypipe 83, the oxygen O₂ is exposed to plasma, and ozone O₃ is therebygenerated, and exhausted from the ozone generator 100. The ozone O₃ thusexhausted is supplied to the reacting tube 81, to oxidize with ozone asurface of the substrate W heated in the reacting tube 81, and exhaustedfrom the exhaust pipe 84. The substrate W after ozone oxidization isterminated is drawn out of the reacting tube 81 together with the boat90.

The ozone generator 100 is made compact, and therefore, can be disposednear the reacting tube 81. Ozone O₃ is self-decomposed even in the gassupply pipe 83, and changed into oxygen O₂. However, when the ozonegenerator can be disposed near the reacting tube 81, consumption ofozone in the stage of supplying ozone O₃ can be reduced as much aspossible. In addition, the degree of freedom of the structure of theozone generator 100 is enhanced, and therefore the ozone generator 100can be directly installed on the reacting tube 81, in the form of anexternal combustion apparatus (so-called “external combustion BOX”) thatgenerates H₂O gas, for example. In this apparatus, the ozone generatorof this embodiment is used, and therefore a plurality of substrates canbe effectively oxidized with ozone.

FIG. 15 shows an example of the structure of the reaction furnace 80 ofthe vertical CVD apparatus. The basic structure of FIG. 15 is the sameas that of FIG. 14. The different point is that in FIG. 15, a mixed gassupply system 89 constituted of a source gas supply line 85 and anoxygen supply line 86 is connected to the gas supply pipe 83. The sourcegas flowing to the source gas supply line 85 is merged with ozone O₃flowing to the oxygen supply line 86, and supplied in the reacting tube81. Note that the source gas supply line 85 and the oxygen supply line86 near a merging part are provided with check valves 87 and 88,respectively.

Ozone gas is used as an oxidizing agent of a CVD, and therefore theozone generator 100 of the embodiment is installed on the oxygen supplyline 86. In this case also, as explained in FIG. 14, the ozone generator100 may be arranged near the reacting tube 81, and may also be installedat the side of a utility which supplies power or the like to thereaction furnace 80, from the viewpoint of maintainability. In thisapparatus, the ozone generator of the embodiment is used, and thereforea CVD film can be effectively formed on the plurality of substrates.

This apparatus, which processes the substrate W by using ozone O₃, isused for forming a SiO₂ film by using TEOS and ozone O₃ by means of aCVD method, as a most typical example. Also, other than this example,this apparatus is also used for forming an Al₂O₃ film by means of an ALDmethod to form an atomic layer one by one by, by alternately supplyingAl (CH₃)₃ and ozone O₃. In addition, as an example of processing otherthan the aforementioned examples, the apparatus is also used whenimproving (C and H, and so forth are picked up by an oxidation force) aHigh-K (high dielectric material) film such as a Ta₂O₅ film and a ZrO₂film formed on the substrate W and the film such as an RuO₂ film used asa material of an electrode, by using ozone.

FIG. 16 shows an example of the structure of the reaction furnace of thesheet wafer-feed type CVD apparatus. The structure of the mixed gassupply system 89 of FIG. 16 is the same as that of FIG. 15, and thedifferent point is that a reaction furnace 110 is not a hot wall batchtype but is a cold wall sheet wafer-feed type. In the reaction furnace110, the substrate W is placed on a susceptor 112 having a heater so asto be heated in a reaction chamber 111 constituting the furnace. Then,the mixed gas led-in from the mixed gas supply system 89 is supplied onthe substrate W, and exhausted from the exhaust port 114. In thisembodiment, the ozone generator of the embodiment is used, and thereforea CVD film can be effectively formed on a single wafer substrate.

FIG. 17 is an example of the structure of the washing apparatus usingozone. Water led-in a filter 123 from a water supply line 122 isfiltered through a filler 124. Meanwhile, ozone O₃ is generated bypassing oxygen O₂ led-in from an oxygen supply line 121 through theozone generator 100 of the embodiment. By leading-in the ozone O₃ in thefilter 123, the ozone O₃ is dissolved in water filtered by the filler124, to produce ozone water. Then, the ozone water thus produced issupplied to an object 120 to be washed such as a reacting tube, areaction chamber, and pipe, to remove a stain. In this embodiment, theozone generator of the embodiment is used, and therefore washing effectscan be enhanced.

FIG. 18 shows an example of the structure of a sheet wafer-feed typeetching device. The basic structure of FIG. 18 is the same as that ofFIG. 16, and the different point is that the source gas supply line andthe check valve are removed and ozone O₃ is supplied to the substrate Win the reaction chamber 111 from the ozone generator 100, and thesurface of the substrate W is subjected to etching. Ashing can be givenas an example of etching. A principle of ashing is shown in FIG. 19. Thesubstrate W is placed on the susceptor 112 having a heater, so as to beheated. A resist film R is formed on the surface of the substrate Wthrough an oxide film Q. The resist film R on the substrate W is removedby using ozone O₃. The ozone O₃ is decomposed by heat so as to beseparated into oxygen O₂ and atomic oxygen O.. Since the atomic oxygenO. has a high activity, the resist film R is decomposed into carbondioxide CO₂ and water H₂O. In addition, ozone O₃ is decomposed intooxygen O₂, and therefore the merit is that a specific detoxifyingapparatus is not required. In this embodiment, the ozone generator ofthe embodiment is used, and therefore etching effects can be enhanced.

FIG. 20 is a block diagram of the sheet wafer-feed type CVD apparatusprovided with an exhaust gas processing apparatus using plasma. TEOS(Tetraethoxysilane) and TRIES (Triethoxysilane) are supplied in thereaction chamber 111 from the source gas supply line 85, and unreactedgas thereof is exhausted from the exhaust port 114. The plasma generator100 of the embodiment is provided in an exhaust pipe 115 connected tothe exhaust port 114. By evacuating the reaction chamber 111 by a pump116 and passing the unreacted gas through the plasma generator 100, theunreacted gas such as TEOS (Tetraethoxysilane) and the TRIES(Triethoxysilane) is decomposed by plasma, and is exhausted in a safeform, which is Si powder or SiO₂ obtained by oxidizing Si powder. Thiscontributes to reducing damage to the pump 116 and a pump life time canbe prolonged. In this embodiment, the plasma generator of the embodimentis used, and therefore exhaust gas processing effects can be enhanced.

(Advantage)

According to the embodiments, the dielectric material is not insertedbetween the electrodes, therefore discharge energy density is increased,and plasma with high efficiency can be generated under the atmosphericpressure. 10 to 1000 times discharge energy density per one dischargecan be obtained compared with the silent discharge having the dielectricmaterial interposed between the electrodes. In addition, by connectingthe arc-extinguishing capacitor in series to the electrode part,intermittent discharge is induced during arc extinguishment, beforebeing switched to the arc discharge from the glow discharge. Therefore,even if the dielectric material is not inserted in the electrode part,damage to the electrode part can be reduced. Accordingly, contaminationgenerated by sputtering is not generated with little damage to theapparatus.

Also, according to the embodiment, one of the metal electrode is formedby a unitized capacitive coupling electrode, and by using the capacitivecoupling electrode thus unitized, the multi-polarized plasma source canbe formed, and free degree of design is thereby increased. In addition,by the array of the capacitive coupling electrodes, for example, theplasma source with high efficiency and large area having various shapesas shown in FIG. 4 to FIG. 8 can be formed.

Further, by individually discharging between the common counterelectrode and the multi-polarized capacitive coupling electrode, aproblem that discharge is hard to be uniformly caused in the space likethe parallel plate electrode, is eliminated, and it becomes easy touniformly cause the discharge even in larger space. Accordingly, theplasma with large area and high density can be easily generated, andozone generation efficiency can thereby be enhanced. Particularly, whenthe capacitive coupling electrode is arranged so as to preventinsulation breakdown between the capacitive coupling electrodes,discharge between the capacitive coupling electrodes (discharge inlateral direction) can be prevented. Therefore, the discharge is notdeviated, and further uniform plasma can be obtained.

Further, the discharge electrode is set as the metal electrode, and themetal electrode is cooled by the refrigerant. Therefore, heat of theelectrode is easily removed, and ozone can be generated at a lowtemperature. Accordingly, decomposition due to the heat of ozone thusgenerated can be effectively prevented. The ozone can be generated withefficiency of 1.0 gO₃/W·hr by the ozone generator using the systemdescribed above. This is a high efficiency of about five times theefficiency 0.22 gO₃/W·hr of the conventional silent discharge. Acondition of this system at this time is that the discharge gap is setto be 1.0 mm; the capacitive coupling electrode is formed by winding acopper foil around a copper bar (φ2 mm) through a silicone thermalcontraction tube; and the arc-extinguishing capacitor is set to be 20 pF(at 100 kHz). Also, the number of electrodes are set to be 20, O₂ flowrate is set to be 10 slm, and high AC voltage is set to be 50 Hz and 10kV_(pp).

MODIFIED EXAMPLE

In the aforementioned embodiment, AC voltage is applied between thecounter electrode and the capacitive coupling electrode, however DCvoltage may be applied therebetween. FIG. 23 shows the modified example,and FIG. 23A is a schematic block diagram of the entire body of theplasma generator, FIG. 23B is a plasma injection power chart of onepole, and FIG. 23C is an equivalent circuit diagram of one pole.

As shown in FIG. 23A, the apparatus is made multi-polarized by arrangingplural capacitive coupling electrodes 20 in such a manner that one endof each floating electrode 21 faces the counter electrode 34. Eachgrounding electrode 23 of the plural capacitive coupling electrodes 20is grounded, and the other end of each floating electrode 21 issimilarly grounded through a resistor R for discharge. Thearc-extinguishing capacitor 13 and the resistor R for discharge arethereby connected in parallel, and a discharge circuit is formed, inwhich the storage charge stored in the arc-extinguishing capacitor C isdischarged through the resistor R for discharge (FIG. 23C). A high DCpower source is connected between the counter electrode 34 and a ground,to thereby apply DC high voltage. A power-assisting capacitor C_(o) isconnected in parallel to a high DC power source.

When DC high voltage exceeding the discharge starting voltage is appliedbetween the counter electrode 34 and the floating electrode 21 by thehigh DC power source, inter-electrodes 34 and 21 is virtually shortcircuited simultaneously with starting discharge, to allow a largecurrent to flow. Therefore, between counter electrode 34 and eachcapacitive coupling electrode 20 is ignited at random and plasma PL isthereby generated in each discharge gap G. Meanwhile, by this current,the charge starts to be stored in the arc-extinguishing capacitor 13.When the arc-extinguishing capacitor 13 is fully charged, the currentstops flowing any more, and the discharge also stops. Specifically, DCpulse discharge is induced, in which the discharge is effected as longas the charge is stored in the arc-extinguishing capacitor 13. Thedischarge stored in the arc-extinguishing capacitor C is discharged bythe resistor R for discharge. By this discharge, the voltage between theelectrodes 34 and 21 is increased, and re-ignition is thereby enabled.The period of the ignition of one capacitive coupling electrode 20 isexpressed by τ≈CR (FIG. 23B). Here, CR refers to a time constant of thedischarge of the storage charge.

When the DC power source is used as a power source, potential of theelectrode to plasma potential can be fixed, and therefore it isadvantageous to be used for a process particularly requiringaccelerating/decelerating efficiency of ion species. However, in thiscase, ½ of injected power is wastefully consumed. That is, a staticenergy stored in the arc-extinguishing capacitor 13 is converted toJoule heat by the resistor R for discharge.

In this way, in the system of the present invention using theself-arc-extinguishing type capacitive coupling electrode, a DC pulseoperation is realized by providing a discharge time constant circuit.This is the characteristic not seen in the silent charge system, andfrom this point of view, free degree of design is enhanced.

INDUSTRIAL APPLICABILITY

The present invention provides a plasma generator having increaseddischarge energy density compared with a silent discharge and capable ofgenerating plasma with high efficiency, with a simple structure. Inaddition, larger discharge energy density contributes to generatingozone with high efficiency. Accordingly, the plasma generator and theozone generator can be restrained from increasing in volume. Moreover,even when the discharge energy density becomes large,self-arc-extinguishing discharge is induced, and this contributes toreducing damage to the electrode part. In addition, when the electrodeis unitized, handling becomes easy.

1. A plasma generator comprising: an electrode part constituted ofplural electrodes; a charge storage part connected with the electrodepart in series for storing charge, and an AC power source for applyingAC voltage to a serial connection circuit formed of the electrode partand the charge storage part, wherein by applying the AC voltage to theserial connection circuit formed of the electrode part and the chargestorage part by the AC power source, discharge is intermittently causedin each inter-electrodes of the plural electrodes of the electrode part,and plasma is thereby generated.
 2. An ozone generator, comprising: anelectrode part constituted of plural electrodes; a charge storage partconnected with the electrode part in series, for storing charge; and anAC power source for applying AC voltage to a serial connection circuitformed of the electrode part and the charge storage part, wherein byapplying the AC voltage to the serial connection circuit formed of theelectrode part and the charge storage part by the AC power source,discharge is caused intermittently in each inter-electrodes of theplural electrodes of the electrode part, and ozone is generated bysupplying gas containing oxygen atom in the discharge atmosphere.
 3. Aplasma generator, comprising: an electrode unit constituted of a firstelectrode, an insulating material or a dielectric material providedaround the first electrode, and a second electrode provided around theinsulating material or the dielectric material; a third electrode facingthe first electrode; and a power source for applying voltage between thesecond electrode and the third electrode, wherein by the power source,the voltage is applied between the second electrode and the thirdelectrode, discharge is thereby caused between the first electrode andthe third electrode, and plasma is thereby generated.
 4. The plasmagenerator according to claim 3, wherein a charge storage part forstoring charge is formed by the first electrode and the secondelectrode, with the insulating material or the dielectric materialinterposed between the first electrode and-the second electrode.
 5. Theplasma generator according to claim 3, wherein by applying AC voltagebetween the second electrode and the third electrode, a pulse dischargeis caused between the first electrode and the third electrode, andplasma is thereby intermittently generated.
 6. The plasma generatoraccording to claim 3, wherein the plasma is generated in an atmosphericpressure.
 7. The plasma generator according to claim 3, wherein theelectrode unit is provided in plural numbers.
 8. The plasma generatoraccording to claim 3, wherein the electrode unit is provided in pluralnumbers around the third electrode.
 9. The plasma generator according toclaim 3, wherein a protrusion portion or a recess portion or an openinghole is provided in a part of the third electrode faced with the firstelectrode.
 10. The plasma generator according to claim 3, wherein thefirst electrode is formed in a bar-shape.
 11. The plasma generatoraccording to claim 3, wherein the first electrode is formed in acylinder-shape.
 12. The plasma generator according to claim 3, whereinthe insulating material or the dielectric material, or/and the secondelectrode are formed in a cylinder shape.
 13. The plasma generatoraccording to claim 3, wherein at least the first electrode or/and thethird electrode are made of metal.
 14. The plasma generator according toclaim 3, wherein the first electrode or/and the third electrode arecooled by refrigerant.
 15. A substrate processing apparatus, comprising:an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material; a third electrode facing the first electrode; and apower source for applying voltage between the second electrode and thethird electrode, wherein by the power source, the voltage is appliedbetween the second electrode and the third electrode, discharge isthereby caused between the first electrode and the third electrode, andin this discharge atmosphere, gas containing oxygen atom is supplied,and ozone is thereby generated.
 16. A substrate processing apparatus,comprising: a processing chamber for processing a substrate; and aplasma generator for generating plasma, wherein the substrate isprocessed by using a reactant obtained by exposing a processing gas tothe plasma generated by the plasma generator, the plasma generatorcomprising: an electrode unit constituted of a first electrode, aninsulating material or a dielectric material provided around the firstelectrode, and a second electrode provided around the insulatingmaterial or the dielectric material; a third electrode facing the firstelectrode; and a power source for applying voltage between the secondelectrode and the third electrode, wherein by applying the voltagebetween the second electrode and the third electrode, discharge iscaused between the first electrode and the third electrode, and plasmais thereby generated.
 17. A substrate processing apparatus, comprising:a processing chamber for processing a substrate; and an ozone generatorfor generating ozone, wherein by using the ozone generated by the ozonegenerator, the substrate is processed, the ozone generator comprising:an electrode unit constituted of a first electrode, an insulatingmaterial or a dielectric material provided around the first electrode,and a second electrode provided around the insulating material or thedielectric material; a third electrode facing the first electrode; and apower source for applying voltage between the second electrode and thethird electrode, wherein by applying the voltage between the secondelectrode and the third electrode, discharge is caused between the firstelectrode and the third electrode, and in such a discharge atmosphere,gas containing oxygen atom is supplied, and ozone is thereby generated.18. A method of manufacturing a semiconductor device, with a plasmagenerator having an electrode unit constituted of a first electrode, aninsulating material or a dielectric material provided around the firstelectrode, and a second electrode provided around the insulatingmaterial or the dielectric material, and a third electrode facing thefirst electrode, the method comprising the steps of: generating plasmaby causing discharge between the first electrode and the third electrodeby applying voltage between the second electrode and the thirdelectrode; and processing a substrate by using a reactant obtained byexposing a processing gas to the plasma thus generated.
 19. The methodof manufacturing the semiconductor device according to claim 18, whereina pulse discharge is caused between the first electrode and the thirdelectrode by applying AC voltage between the second electrode and thethird electrode, and plasma is thereby intermittently generated in theplasma generating step.
 20. The method of manufacturing thesemiconductor device according to claim 18, wherein the substrate isprocessed in the substrate processing step by using ozone obtained byexposing gas containing oxygen atom to atmosphere where the discharge iscaused.
 21. A plasma generator, comprising: an electrode partconstituted of plural electrodes; plural charge storage parts connectedin series to the electrode part to store charge; and an AC power sourcefor applying AC voltage to a circuit in which the plural serialconnection parts formed of the electrode part and the plural chargestorage parts are connected in parallel, wherein by applying the ACvoltage by this AC power source to the circuit in which the serialconnection part formed of the electrode part and the plural chargestorage parts are connected in parallel, discharge is intermittentlycaused between plural electrodes of the electrode part, and plasma isthereby generated.